A computer network is a collection of interconnected computing devices that can exchange data and share resources. In a packet-based network, such as an Ethernet network, the computing devices communicate data by dividing the data into variable-length blocks called packets, which are individually routed across the network from a source device to a destination device. The destination device extracts the data from the packets and assembles the data into its original form.
Certain devices, referred to as routers, maintain routing information representative of a topology of the network. The routers exchange routing information so as to maintain an accurate representation of available routes through the network. A “route” can generally be defined as a path between two locations on the network. Upon receiving an incoming data packet, a router examines information within the packet, often referred to as a “key,” to select an appropriate next hop to which to forward the packet in accordance with the routing information.
Routers may include one or more forwarding components, e.g., packet forwarding engines, interconnected by an internal switch fabric. Packet forwarding engines receive and send data with other external devices via interface cards. The switch fabric provides an internal interconnect mechanism for forwarding data within the router between the packet forwarding engines for ultimate transmission over a network. In some examples, a router or switching device may employ a distributed, multi-stage switch fabric architecture, in which network packets traverse multiple stages of the switch fabric located in distributed forwarding components of the router to travel from an ingress point of the switch fabric to an egress point of the switch fabric.
A router may be virtualized into multiple virtual network nodes by portioning hardware resources of the router, such as packet forwarding engines. One or more links may be provisioned between two virtual nodes. For example, an aggregated fabric interface (AF) link that is a logical link construct and provides virtual node connectivity. A source packet forwarding engine may load balance incoming data across the internal switch fabric via the AF link towards a destination packet forwarding engine for ultimate transmission over a network.